Flanged cam follower

ABSTRACT

A cam follower includes a shaft and a hub rotatable with respect to the shaft via at least one bearing. A flanged tire is affixed to the outer peripheral surface of the hub, the flanged tire having a main body portion and a flange portion extending radially outwardly therefrom. The main body portion and the flange portion are integrally formed from a polymeric material, and the hub, the main body portion and the flange portion are disposed so as to define a generally planar outer surface. A flange support plate, having a support plate outer diameter that is generally equal to or greater than the flange diameter, is positioned abutting the generally planar outer surface and is rigidly affixed to the hub, the flange support plate being formed from a metal material, thereby providing structural support to the flange portion for axial forces applied to the flange portion.

FIELD OF THE INVENTION

The present invention relates generally to a cam follower, and moreparticularly to a flanged cam follower adapted to bear loads both ingenerally radial, as well as generally axial, directions.

BACKGROUND OF THE INVENTION

Flanged cam followers are used for a variety of purposes, such as toenable linear motion of an object on a rail. They are generally used inpairs for such applications, each mounted on the opposing side of theobject, with the flanges running on the side of the rail, preventing theobject from sliding off the rail. The flanges are designed to carry anyside load (i.e., generally axial to the cam followers) that mightdevelop when the object is moving.

Traditional flanged cam followers are made of metal in order to providethe structural integrity needed to withstand repeated and potentiallysubstantial axial loads. Attempts to create polymer flanged camfollowers have generally resulted in the flanges being prone to beingsheared off when significant axial loads are applied thereto,particularly when those loads are repeated over time.

Metal flanged cam followers, however, suffer from various disadvantagesof their own. Metal flanged cam followers are subject to wear as aresult of repeated contact with a rail. A conventional cammingarrangement includes a metal rail and one or more mating pairs of metalflanged cam followers, each having one or more contact surfaces. As theflanged cam followers contact the rail, the metal of the cam followers,as well as the metal of the rail, become worn and both the flanged camfollowers and the rail need to be replaced. The replacement of the railand the flanged cam followers requires a prolonged down time, andconsequently involves significant direct and indirect costs.

In addition, metal rails and metal flanged cam followers requirelubrication, such as grease, oil, or other lubricating substances (i.e.,lubrication on the rail to prolong its life and internal lubrication ofthe cam follower). In clean applications (e.g., food processing,pharmaceutical processing, etc.), this lubrication can damage, corruptand/or contaminate the material being processed (e.g., food, medicine,packaging, etc.) or other components or machines in the process. Thus,the maintenance, replacement and repair of metal flanged cam followersrequires a substantial amount of time because the lubrication materialneeds to be properly applied, and even then, this does not completelysolve the problem of excess lubrication causing problems with theprocess.

Over-greasing of the metal flanged cam follower is also a commonoccurrence. When the inside of the cam follower is packed with too muchgrease, the cam follower has a very high resistance to rolling and tendsto slide on the metal surface of the rail. This causes excessive railwear as well as the development of a flat surface on the flanged camfollower. Metal cam followers that develop a flat surface will not turnand have to be replaced.

In addition, over time, the lubrication decreases and a contact surfaceof the rail begins to rub directly against a contact surface of themetal flanged cam follower. This may result in noise (e.g., squeaking),decreased performance (e.g., slower operating speed, higher operatingtemperature), or even complete failure. Moreover, even if the failure isnot catastrophic, metal particles may be formed, thereby leading to thepotential for particulate contamination.

Furthermore, as is well known, metals are, in general, excellentelectrical conductors. While this may, of course, be desirable in somecircumstances, in the context of rails and their associated flanged camfollowers, a high degree of electrical insulation is often preferredinstead. Thus, provision of a polymer cam follower, which are generallyexcellent electrical insulators, would be advantageous.

The present invention, therefore, aims to provide a flanged polymericcam follower, with its attendant benefits (e.g., reduced or norequirement for lubrication on the rail or the bearings, reduced or norail wear, reduced noise, excellent electrical insulation), while at thesame time ensuring the structural integrity needed to withstand repeatedand potentially substantial axial loads, particularly on the flangeportion of the cam follower.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a cam followerincludes a shaft extending from a first axial shaft end to a secondaxial shaft end and a hub defining an interior area with at least onebearing disposed therein, the at least one bearing being disposed overthe first axial shaft end such that the hub is rotatable with respect tothe shaft via the at least one bearing, the hub further defining anouter peripheral surface. A flanged tire is affixed to the outerperipheral surface of the hub and is rotatable with the hub with respectto the shaft, the flanged tire having a main body portion with agenerally cylindrical outer surface with a main body diameter and havinga flange portion extending radially outwardly from the generallycylindrical outer surface of the main body portion, the flange portionhaving a flange diameter that is larger than the main body diameter. Themain body portion and the flange portion are integrally formed from apolymeric material, and the hub, the main body portion and the flangeportion are disposed so as to define a generally planar outer surfacefacing the second axial shaft end. A flange support plate, having asupport plate outer diameter that is generally equal to or greater thanthe flange diameter, is positioned abutting the generally planar outersurface and is rigidly affixed to the hub, the flange support platebeing formed from a metal material, thereby providing structural supportto the flange portion for forces applied to the flange portion in adirection normal to the generally planar outer surface.

In some embodiments, the outer peripheral surface of the hub isgenerally cylindrical. In certain of these embodiments, the outerperipheral surface of the hub has protrusions, recesses or bothprotrusions and recesses thereon in order to enhance attachment of theflanged tire to the hub. In certain of these embodiments, the outerperipheral surface of the hub is knurled in order to enhance attachmentof the flanged tire to the hub.

In some embodiments, the hub is formed from a metal material. In certainof these embodiments, the hub is formed from stainless steel. In certainof these embodiments, the flange support plate is formed from stainlesssteel.

In some embodiments, the at least one bearing comprises at least twobearings. In certain of these embodiments, the at least one bearingcomprises at least three bearings.

In some embodiments, the second axial shaft end comprises a fasteneradapted to attach the shaft to another component. In certain of theseembodiments, the fastener of the second axial shaft end comprises athreaded portion.

In some embodiments, the main body portion and the flange portion of theflanged tire are monolithic. In certain of these embodiments, the mainbody portion and the flange portion of the flanged tire are formed froma polyamide material.

In some embodiments, a plurality of fasteners are provided for rigidlyaffixing the flange support plate to the hub. In certain of theseembodiments, the fasteners are screws passing through holes in theflange support plate and engaging threaded openings in the hub.

In some embodiments, the flange support plate includes an openingpassing therethrough having an inner support plate diameter, wherein theopening passing through the flange support plate is sized and positionedto accommodate the shaft. In certain of these embodiments, the interiorarea of the hub has an inner hub diameter and the inner support platediameter is smaller than the inner hub diameter, whereby the at leastone bearing is retained in the interior area of the hub by the flangesupport plate.

In accordance with another aspect of the present invention, a camfollower includes a shaft extending from a first axial shaft end to asecond axial shaft end, the second axial shaft end comprising a fasteneradapted to attach the shaft to another component, and a hub defining aninterior area with at least one bearing disposed therein, the at leastone bearing being disposed over the first axial shaft end such that thehub is rotatable with respect to the shaft via the at least one bearing,the hub being formed from a metal material and further defining agenerally cylindrical outer peripheral surface having protrusions,recesses or both protrusions and recesses formed thereon. A flanged tireis affixed to the outer peripheral surface of the hub and is rotatablewith the hub with respect to the shaft, the flanged tire having a mainbody portion with a generally cylindrical outer surface with a main bodydiameter and having a flange portion extending radially outwardly fromthe generally cylindrical outer surface of the main body portion, theflange portion having a flange diameter that is larger than the mainbody diameter. The main body portion and the flange portion areintegrally formed from a monolithic piece of polymeric material, and thehub, the main body portion and the flange portion are disposed so as todefine a generally planar outer surface facing the second axial shaftend. A flange support plate having a support plate outer diameter thatis generally equal to or greater than the flange diameter, abuts thegenerally planar outer surface and is rigidly affixed to the hub by aplurality of threaded fasteners passing through holes in the flangesupport plate and engaging threaded openings in the hub. The flangesupport plate includes an opening passing therethrough having an innersupport plate diameter, the opening passing through the flange supportplate being sized and positioned to accommodate the shaft. The flangesupport plate is formed from a metal material, thereby providingstructural support to the flange portion for forces applied to theflange portion in a direction normal to the generally planar outersurface.

In some embodiments, the outer peripheral surface of the hub is knurledin order to enhance attachment of the flanged tire to the hub. In someembodiments, the hub is formed from stainless steel. In certain of theseembodiments, the flange support plate is formed from stainless steel.

In some embodiments, the at least one bearing comprises at least twobearings. In certain of these embodiments, the at least one bearingcomprises at least three bearings.

In some embodiments, the fastener of the second axial shaft endcomprises a threaded portion. In some embodiments, the main body portionand the flange portion of the flanged tire are formed from a polyamidematerial. In some embodiments, the interior area of the hub has an innerhub diameter and the inner support plate diameter is smaller than theinner hub diameter, whereby the at least one bearing is retained in theinterior area of the hub by the flange support plate.

Other features and advantages of the invention will become more apparentfrom consideration of the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top isometric view of a flanged polymeric cam follower inaccordance with an exemplary embodiment of the present invention;

FIG. 2 is a bottom isometric view of the flanged polymeric cam followerof FIG. 1 ;

FIG. 3 a bottom plan view of the flanged polymeric cam follower of FIGS.1 and 2 ;

FIG. 4 is a side partially cross-sectional view of the flanged polymericcam follower of FIGS. 1-3 , taken along line 4-4 of FIG. 3 ;

FIGS. 5A and 5B are, respectively, side isometric and side elevationalviews of a shaft portion of the flanged polymeric cam follower of FIGS.1-4 ;

FIGS. 6A and 6B are, respectively, bottom isometric and side partiallycross-sectional views of a flanged tire portion of the flanged polymericcam follower of FIGS. 1-4 ; and

FIGS. 7A and 7B are, respectively, bottom isometric and side partiallycross-sectional views of a flange support plate portion of the flangedpolymeric cam follower of FIGS. 1-4 .

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. Exemplary embodimentsof the present invention describe flanged cam followers in railapplications, i.e., where the cam follower is contacting a rail system,such as in a conveyor system. It should be understood, however, that thepresent invention may be implemented in any camming arrangement thatutilizes a flanged cam follower. Indeed, the flanged cam follower of thepresent invention is suitable for any application where a flanged camfollower is used, subject to the environmental capabilities of thematerials being used.

As shown in FIGS. 1-4 , the flanged cam follower (10) of the presentinvention generally includes a shaft (12), a hub (14) rotatable aboutthe shaft (12) via three ball bearings (16, 18, 20), a flanged tireaffixed to the hub (14) and rotatable with the hub (14) about the shaft(12), and a flange support plate (22) rigidly affixed to the hub (14).Each of these elements, along with their configuration and operation,will be described in more detail below.

As best seen in FIGS. 4, 5A and 5B, the shaft (12) includes a face (24)at the first axial end (26) thereof perpendicular to an axis of rotation(A) of the flanged cam follower (10). The face (24) has a recessedhexagonal socket (28) configured to receive a hex wrench, or the like,for rotating the shaft (12) about the axis of rotation (A). The shaft(12) further includes a plurality of threads (30) on a radial outsidesurface of the shaft (12) at the second axial end (32) thereof. In thisway, the shaft (12) can be received in a bore (not shown) comprising acomplementary thread pattern or can similarly be received in a nut orthe like having a complementary thread pattern. If desired, the shaft(12) may optionally also include a hollow portion (not shown) to allowfor weight reduction of the shaft (12) for efficiency of operation.

Referring now to FIGS. 6A and 6B in addition to FIGS. 1-4 , the hub (14)defines a generally cylindrical hollow interior area (34) with the ballbearings (16, 18, 20) disposed therein, as best seen in FIG. 4 . One endof the interior area (34) is provided with a shoulder (36), which abutsthe ball bearing (16) so as to retain the ball bearings (16, 18, 20)within the interior area (34), as more fully described below. Duringassembly, the ball bearings (16, 18, 20) are inserted into the interiorarea (34) from the right (with respect to the orientation shown in FIG.4 ) and moved toward the left until the ball bearing (16) abuts theshoulder (36). While three ball bearings (16, 18, 20) are shown, asmaller or larger number of ball bearings may be employed instead.Moreover, other types of bearings, such as roller bearings, may be usedin addition to, or instead of, ball bearings.

The ball bearings (16, 18, 20) are disposed over the first axial end(26) of the shaft (12) such that the hub (14) is rotatable with respectto the shaft (12) via the ball bearings (16, 18, 20). The ball bearings(16, 18, 20), and consequently the hub (14), may be axially retained onthe shaft (12) by provision of a shoulder (38) on the shaft (12) whichabuts ball bearing (20), and by another shoulder, flange, retaining clipor the like (40) (best seen in FIG. 4 ) abutting ball bearing (16). Thehub (14) is preferably formed from a metal material to provide robuststructural support. In some situations, the hub (14) is formed fromstainless steel, which is particularly well-suited for use in corrosiveenvironments.

The hub (14) further defines an outer peripheral surface (42) which may,in some embodiments, be generally cylindrical. Such is not strictlynecessary however, and if desired, the outer peripheral surface (42) mayhave other shapes, such as being polygonal, frustoconical, etc.

Still referring to FIGS. 1-4, 6A and 6B, a flanged tire (44) is affixedto the outer peripheral surface (42) of the hub (14), such that theflanged tire (44) is rotatable with the hub (14) with respect to theshaft (12). The flanged tire (44) defines a main body portion (46) witha generally cylindrical outer surface (48) with a main body diameter(D1) and a flange portion (50) extending radially outwardly from thegenerally cylindrical outer surface (48) of the main body portion (46).The flange portion (50) has a flange diameter (D2) that is larger thanthe main body diameter (D1).

The main body portion (46) and the flange portion (50) of the flangedtire (44) are integrally formed from a polymeric material. In certainsituations, it is desirable for the flanged tire (44) to formed from apolyamide material, such as a nylon. While the main body portion (46)and the flange portion (50) may be formed separately and then joinedtogether to form an integral piece, it is preferred for the main bodyportion (46) and the flange portion (50) to be formed as a single,monolithic piece, for example, by injection molding or the like. Such amonolithic configuration is generally known to provide enhancedstructural integrity, as compared to separately formed componentssubsequently being joined together.

The flanged tire (44) may be affixed to the outer peripheral surface(42) of the hub (14) by various means, such as by friction fit, byapplication of adhesives, by ultrasonic welding, etc. However, in apreferred embodiment, the flanged tire (44) is directly molded onto theouter peripheral surface (42) of the hub (14). In order to enhance thebond between the flanged tire (44) and the hub (14), and as best seen inFIG. 1 , the outer peripheral surface (42) of the hub (14) may haveprotrusions, recesses or both protrusions and recesses (14′) providedthereon in order to enhance attachment of the flanged tire (44) to thehub (14). As one specific example, the outer peripheral surface (42) ofthe hub (14) is knurled in order to enhance attachment of the flangedtire (44) to the hub (14).

As can best be seen in FIGS. 6A and 6B, the hub (14), the main bodyportion (46) and the flange portion (50) of the flanged tire (44) aredisposed so as to define a generally planar outer surface (52) facingthe second axial shaft end (32) (as seen in FIG. 4 ).

Referring now specifically to FIGS. 7A and 7B in addition to FIGS. 1-4 ,the flange support plate (22) abuts the generally planar outer surface(52) of the flanged tire (44) and is rigidly affixed to the hub (14),for example, by a plurality of fasteners (54). In the embodiment shown,the fasteners (54) take the form of screws passing through holes (56) inthe flange support plate (22) engaging threaded openings (58) in the hub(14). As shown, the fasteners (54) and the holes (56) in the flangesupport plate (22) may be beveled such that the fasteners (56) are flushwith the flange support plate (22) when assembled, as shown in FIG. 4 .Three fasteners (54) are shown in the FIGS., though a smaller or largernumber may be provided.

The flange support plate (22) is formed from a metal material, withstainless steel being preferred in some applications, particularly incorrosive environments. The flange support plate (22) has a supportplate outer diameter (D3) that is generally equal to or greater than theflange diameter (D2) of the flange portion (50) of the flanged tire(44), so as to support the flange portion (50) over its entire extent,thereby providing structural support to the flange portion (50) foraxial forces, i.e., forces applied to the flange portion (50) in adirection normal to the generally planar outer surface (52).

The flange support plate (22) also includes an opening (60) passingtherethrough having an inner support plate diameter (D4), with theopening (60) being sized and positioned to accommodate the shaft (12),as best seen in FIG. 4 . The inner support plate diameter (D4) ispreferably smaller than the inner hub diameter (D5) of the interior area(34) of the hub (14) such that when the flange support plate (22) isaffixed to the hub (14), the opening (60) in the flange support plate(22) defines a shoulder (62) so as to retain the ball bearings (16, 18,20) between shoulder (62) and shoulder (36), as best seen in FIG. 4 .Also as shown in FIG. 4 , the combined thickness of the ball bearings(16, 18, 20) is preferably approximately equal to the distance betweenthe shoulder (62) and the shoulder (36) so as to minimize axial playbetween the various components.

Provision of a metal hub (14) provides several advantages over an allpolymer design, including the following: a metal hub (14) supports thepolymer flanged tire (44) on the entire length thereof and evenlydistributes the radial load to the ball bearings (16, 18, 20), whichtranslates into higher load-bearing capacity; a metal hub (14) can betapped and threaded to securely mount the flange support plate (22)thereto; a metal hub (14) can be formed from stainless steel forcorrosive environments; and a metal hub (14) provides enhanced safety(i.e., in case the polymer flanged tire (44) is destroyed, movingobjects will stay on the rail).

Provision of a polymer flanged tire (44), on the other hand, alsoprovides several advantages, including the following: no lubrication isrequired on the rail or the bearings (bearings are lubricated for life);there is no rail wear, which results in substantial savings on replacingworn-out rails (e.g., on palletizers); with a polymer flanged tire (44),there is no grease and metal particulate contamination; a polymerflanged tire (44) reduces noise by up to 10 dB, as compared to metal camfollowers; and a polymer flanged tire (44) presents a polymer contactsurface with the metal rail, which is an excellent electrical insulator.

Although the invention has been described with reference to a particulararrangement of parts, features and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

What is claimed is:
 1. A cam follower comprising: a shaft extending froma first axial shaft end to a second axial shaft end; a hub defining aninterior area with at least one bearing disposed therein, the at leastone bearing being disposed over the first axial shaft end such that saidhub is rotatable with respect to said shaft via the at least onebearing, said hub further defining an outer peripheral surface; aflanged tire affixed to the outer peripheral surface of said hub androtatable with said hub with respect to said shaft, said flanged tirehaving a main body portion with a generally cylindrical outer surfacewith a main body diameter and having a flange portion extending radiallyoutwardly from the generally cylindrical outer surface of the main bodyportion, the flange portion having a flange diameter that is larger thanthe main body diameter; wherein the main body portion and the flangeportion are integrally formed from a polymeric material; wherein saidhub, the main body portion and the flange portion are disposed so as todefine a generally planar outer surface facing the second axial shaftend; and a flange support plate having a support plate outer diameterthat is generally equal to or greater than the flange diameter, saidflange support plate abutting the generally planar outer surface andbeing rigidly affixed to said hub, said flange support plate beingformed from a metal material, thereby providing structural support tothe flange portion for forces applied to the flange portion in adirection normal to the generally planar outer surface.
 2. The camfollower of claim 1 wherein the outer peripheral surface of said hub isgenerally cylindrical.
 3. The cam follower of claim 2 wherein the outerperipheral surface of said hub has protrusions, recesses or bothprotrusions and recesses thereon in order to enhance attachment of saidflanged tire to said hub.
 4. The cam follower of claim 3 wherein theouter peripheral surface of said hub is knurled in order to enhanceattachment of said flanged tire to said hub.
 5. The cam follower ofclaim 1 wherein said hub is formed from a metal material.
 6. The camfollower of claim 5 wherein said hub is formed from stainless steel. 7.The cam follower of claim 6 wherein said flange support plate is formedfrom stainless steel.
 8. The cam follower of claim 1 wherein the atleast one bearing comprises at least two bearings.
 9. The cam followerof claim 8 wherein the at least one bearing comprises at least threebearings.
 10. The cam follower of claim 1 wherein the second axial shaftend comprises a fastener adapted to attach said shaft to anothercomponent.
 11. The cam follower of claim 10 wherein the fastener of thesecond axial shaft end comprises a threaded portion.
 12. The camfollower of claim 1 wherein the main body portion and the flange portionof said flanged tire are monolithic.
 13. The cam follower of claim 12wherein the main body portion and the flange portion of said flangedtire are formed from a polyamide material.
 14. The cam follower of claim1 further comprising a plurality of fasteners rigidly affixing saidflange support plate to said hub.
 15. The cam follower of claim 14wherein the fasteners are screws passing through holes in said flangesupport plate and engaging threaded openings in said hub.
 16. The camfollower of claim 1 wherein said flange support plate includes anopening passing therethrough having an inner support plate diameter,wherein the opening passing through said flange support plate is sizedand positioned to accommodate said shaft.
 17. The cam follower of claim16 wherein the interior area of said hub has an inner hub diameter andwherein the inner support plate diameter is smaller than the inner hubdiameter, whereby the at least one bearing is retained in the interiorarea of the hub by said flange support plate.
 18. A cam followercomprising: a shaft extending from a first axial shaft end to a secondaxial shaft end, the second axial shaft end comprising a fasteneradapted to attach said shaft to another component; a hub defining aninterior area with at least one bearing disposed therein, the at leastone bearing being disposed over the first axial shaft end such that saidhub is rotatable with respect to said shaft via the at least onebearing, said hub being formed from a metal material and furtherdefining a generally cylindrical outer peripheral surface havingprotrusions, recesses or both protrusions and recesses formed thereon; aflanged tire affixed to the outer peripheral surface of said hub androtatable with said hub with respect to said shaft, said flanged tirehaving a main body portion with a generally cylindrical outer surfacewith a main body diameter and having a flange portion extending radiallyoutwardly from the generally cylindrical outer surface of the main bodyportion, the flange portion having a flange diameter that is larger thanthe main body diameter; wherein the main body portion and the flangeportion are integrally formed from a monolithic piece of polymericmaterial; wherein said hub, the main body portion and the flange portionare disposed so as to define a generally planar outer surface facing thesecond axial shaft end; and a flange support plate having a supportplate outer diameter that is generally equal to or greater than theflange diameter, said flange support plate abutting the generally planarouter surface and being rigidly affixed to said hub by a plurality ofthreaded fasteners passing through holes in said flange support plateand engaging threaded openings in said hub, said flange support plateincluding an opening passing therethrough having an inner support platediameter, wherein the opening passing through said flange support plateis sized and positioned to accommodate said shaft, said flange supportplate being formed from a metal material, thereby providing structuralsupport to the flange portion for forces applied to the flange portionin a direction normal to the generally planar outer surface.
 19. The camfollower of claim 18 wherein the outer peripheral surface of said hub isknurled in order to enhance attachment of said flanged tire to said hub.20. The cam follower of claim 18 wherein said hub is formed fromstainless steel.
 21. The cam follower of claim 20 wherein said flangesupport plate is formed from stainless steel.
 22. The cam follower ofclaim 18 wherein the at least one bearing comprises at least twobearings.
 23. The cam follower of claim 22 wherein the at least onebearing comprises at least three bearings.
 24. The cam follower of claim18 wherein the fastener of the second axial shaft end comprises athreaded portion.
 25. The cam follower of claim 18 wherein the main bodyportion and the flange portion of said flanged tire are formed from apolyamide material.
 26. The cam follower of claim 18 wherein theinterior area of said hub has an inner hub diameter and wherein theinner support plate diameter is smaller than the inner hub diameter,whereby the at least one bearing is retained in the interior area of thehub by said flange support plate.